A separator, sometimes referred to as a “lath”, “stick”, “sticker”, or “crosser”, is used in the lumber industry to separate lumber in a stack, sometimes referred to as a “bundle” or “lift”. In the lumber industry, timber is cut into boards or lumber and stacked in a shed or kiln to dry before shipping. The boards in a stack of lumber are spaced apart by separators usually placed transversely to the length of the boards. A stack of lumber is made of a number of boards placed in spaced apart and parallel layers.
Stacks of lumber may be placed on top of one another using spacer blocks between each stack. The spacer blocks are normally larger than a separator, but both are normally made from the same material, for example, a low grade lumber such as spruce. Spacer blocks separate the bottom layer of lumber from the ground or the stack below and provide sufficient space to permit access beneath the bottom layer, for example, with the forks of a lift truck for lifting and transporting the stack or lumber. A separator is typically about 1″ thick, while a spacer block is typically about 4″ thick. As used herein, the term “separator” includes spacer blocks.
One problem with the use of separators is the imprint or stain, sometimes referred to as a “shadow” or “sticker stain”, which can be left on the boards in a stack where they have been in contact with the separators. This staining may render the lumber unmerchantable for certain end uses.
Various attempts have been made to resolve the stain problem in the lumber industry, as for example, modifying the surface of the separator which comes into contact with the boards in a stack to minimize the contact area or maximize airflow between the separators and the boards. With the use of separators the stability of a stack of lumber is a concern when it is being moved, for example, on the forks of a lift truck in a lumber yard on uneven terrain. Relative motion between the layers in a stack can result in movement of the stack or spillage during transport, whereby the stack loses its structural integrity and presents a safety risk to workers handling stacks of lumber.